Re: Running makemandb on every boot
Robert Elz <[email protected]>
| Newsgroups | gmane.os.netbsd.ports.mac68k,gmane.os.netbsd.current,gmane.os.netbsd.ports.vax |
|---|---|
| Message-ID | <[email protected]> |
Date: Mon, 19 May 2014 11:29:54 -0400
From: Greg Troxel <[email protected]>
Message-ID: <[email protected]>
| So rather than make running this on boot configurable, it seems better
| to perhaps schedule it with some sort of "run this once" faciltiy,
In the interests of contributing more than noise, I offer the following
script that fell off the back of a truck somewhere (it is public domain,
unlicenced, unlicenceable as its author will never claim it - I guarantee
that...)
Feel free to do what you like with it, its objective is to run commands
(from cron usually) so they can be specified to both run @boot, and at some
fixed time of day/week/.. whatever is needed. Cron (or similar) takes care
of making sure it gets run (when properly configure) this script arranges to
make sure that the command is run no more than once a day/week/month/year (or
fortnight, though that option is little tested, somewhat weird by design, and
may be buggy).
If this is deemed useful enough to consider, you never know, but that a man
page might fall off another truck sometime...
kre
ONCE-A.SH
(application/x-sh, 2 KB)
#! /bin/sh
#
# Once-a whatever do some command
#
# Designed to be run from cron, periodically, and @boot
# to arrange that the command is executed once, but not
# more often than that, each period. Making sure it is
# executed at least once is a job for correctly setting
# up crontab, preventing more than once is what this script
# handles.
#
# Succeed or fail, the command is run just once per period.
#
# Caution: system crashes just when this script is running could
# allow the command to run twice (once just before, and again
# immediately after) the crash (if the record file is not
# correctly updated) or never for the period (if the record
# file does get updated, but the command does not get started.)
#
# This kind of thing should be very rare...
#
DB=/var/db/once-a
EXCODE=99
usage()
{
echo >&2 "Usage: $0 period cmd [args]"
echo >&2 " preiod: day | week | fortnight | month | year"
echo >&2 " or 'test' just to verify setup"
exit ${EXCODE}
}
case "$#" in
[01]) usage;;
esac
case "${LOGNAME}" in
'') LOGNAME=${USER:-$( id -un $)};;
esac
DB="${DB}/${LOGNAME}"
test -d "${DB}" || {
echo >&2 "Once-a database directory does not exist: ${DB}"
exit ${EXCODE}
}
echo "Testing" > "${DB}/Test" || {
echo >&2 "Once-a database directory ($DB) not writeable"
exit ${EXCODE}
}
rm -f "${DB}/Test"
period=$1; shift
cmd=$1; shift
case "${period}" in
[Tt]est) exit 0;;
[Dd]ay) fmt="%Y %m %d";;
[Ww]eek) fmt="%Y %U";;
[Ff]ortnight) fmt="%Y %U";; # Don't change this one!
[Mm]onth) fmt="%Y %m";;
[Yy]ear) fmt="%Y";;
*) usage;;
esac
BASE=$(basename "${cmd}")
test -s "${DB}/${BASE}" && {
LAST=$(cat "${DB}/${BASE}")
NOW=$(date +"${fmt}")
case "${period}" in
[Ff]ortnight)
set -$- ${NOW} "$@";
Y=$1; W=$2; shift 2
set -$- ${LAST} "$@";
LY=$1; LW=$2; shift 2
test ${LY} -lt ${Y} && W=$(( $W + 52 ))
W=$(( $W / 2 ))
LW=$(( $LW / 2))
test $W -eq $LW && exit 0
;;
*) test "${LAST}" = "${NOW}" && exit 0;;
esac
}
date +"${fmt}" > "${DB}/${BASE}"
exec "${cmd}" "$@"